and since getweb depends on non-free software and is a part of the package, foo2zjs as a whole is considered to depend on non-free software.
No. getweb *downloads* and copies some non-free software, it does not depend on it.
does getweb function correctly if the external files are unable to bedownloaded? if the answer is no, then the script must be considered to depend on those files. and since those external files contain non-free data, then the script must be considered to depend on non-free data.
this is pretty straightforward logic.